help ! 1.0X/1.5X Charge Pump DC/DC Converter

Dear All:
I am designing a 1.0X/1.5X Charge Pump DC/DC Converter,but at 1.5X mode, my converter just converter to 1.3X. Can anyone help me to how to
design the switching converter to meet the 1.5X function?

You are not working on Dickson type charge pump but switched capacitor.
As I know,cascading one more stage if you are using swiched capacitor charge pump.

thank you , sir. I think I know what you mean...

what's the topology of your Charge Pump?

The best method will be to add one more stage to have the capability to generate more than 1.5times vpwr in no load and then add a feedback network to stabilize the voltage at ur desired value. Even loading it wont reduce the value of output voltage. Hope this helps.

It's nice to first generate higher than 1.5x voltage, then place a MOS in series at output, use feedback to control gate of MOS.

You can either use PMOS (just like a LDO) or a NMOS (HDO) for the regulation.

I prefer HDO approach because even at the frequency beyond your close loop bandwidth, Rout still remains low (assume IL is significant) while LDO Rout drastically increases.

The catch is how to make HDO gate drive voltage free of ripple (since you might have to tap it from the high voltage available) -- I will leave it to your innovation. :twisted: :roll:

If output voltage ripple is not concern, you might easily get away by making the switch MOS into variable resistor through output feedback. That's exactly what TI did in their parts. :!: